Why do I see strange echos around images from a stereo microscope?
Stereo microscopes, while often producing excellent source images for this application, may also present particular challenges as the objective moves a considerable distance relative to the sample. Lighting If a reflective sample (eg. a metalic object) is lit by a ring-illuminator around the microscope objective, the angle of lighting will change and may cause transient highlights as the microscope is focussed on successive planes. If a transparent or translucent sample (eg. sand grains, glass structures) is lit transmissively, refractive effects may cause moving halos as the microscope is focussed on successive planes. Fiber-optic gooseneck illuminators may offer more consistent lighting in both cases above. Parallax The three-dimensional shape of some samples (eg. seashells, mechanical components) may cause some regions to be occluded by other parts of the same sample as the microscope is focussed on successive planes. This is a particular problem where the base of the sample is unde
